1. Field of the Invention
The invention relates to integrated circuit (IC) packages and more particularly to a wafer level chip scale package and a mask for fabricating the same.
2. Description of the Related Art
Solid state electronic devices, more colloquially known as semiconductor chips or dies, are typically manufactured from a semiconductor substrate material such as silicon, germanium or gallium/arsenide. Circuitry is formed on one surface of the device with input and output pads formed around the periphery or central position to facilitate electrical connection with a host electrical apparatus.
An essential step in the manufacturing of solid state electronic devices is the packaging step. Packaging involves mechanical and environmental protection of a semiconductor chip and provides electrical interconnection between predetermined locations on the semiconductor chip and external electrical terminals.
Existing packaging techniques for mounting a semiconductor die on a substrate via the bonding points on both the die and the substrate include ball grid array (BGA), wire bonding, and flip chip. The inner traces aid in fan out the bonding points on the bottom of the substrate. The solder balls are separately planted on the bonding points to serve as an interface for electrical connection of the die to the external circuitry.
Recently, wafer level chip scale package (WLCSP) technology, a new packaging technology, has received attention as a formidable three-dimensional mounting technology. The WLCSP provides a small package having about the same outside dimensions as a die packaged therein. Further, WLCSP is advantageous in enabling printing of the redistribution circuit directly on the die by using the peripheral area of the die as the bonding points. This is made possible by redistributing an area array on the surface of the die, allowing the entire area of the die to be fully utilized. The bonding points are located on the redistribution circuit by forming flip chip bumps, thus, the bottom side of the die connects directly to the printed circuit board (PCB) with micro-spaced bonding points.